A post from last month:
AC works great - no problems.
When switching over to Heat there is nothing; the circit board on the heater is getting power but nothing is turing on. The Honeywell Tstat is showing "HEAT ON"

Trouble Shooting so far:
Installed new 5 wire from the Tstat to the Heater/AC unit
All the color wires match up from the tsat to heater
Fan does spin if I use my finger to move it (not seized)

Any suggestions would be great!

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Replied with "Fixed.. Bad T-Stat
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Now my issue:

Same Problem...Changed the T-Stat, still nothing. Circiut board making a loud "Crackling noise".
I have a Ducane Gas Furnace
Model CMPE075U3
Downflow/Horizontial Right

Old T-Stat.. Old mercury kind
Replaced with Honeywell RTH7600 Touchscreen Programmable.

I was able to get cool air from it, now when you switch to either or you hear that noise from the board, like a swoosh crackling sound.

Any ideas?
Thank you in advance.

What codes is the circuit board showing?

Where would I find this at? The LED on the ignitor is showing the "normal heartbeat" (Bright - Dim - Bright)

If this is your furnace there should be a circuit board in it that controls the unit.

http://www.ducanehvac.com/pdfs/20590702.pdf

The circuit board has a lite that flashes a blink code. When you get the blink code(count the number of blinks) you can look on the inside of the blower door on the wiring diagram and you can read what the code says is wrong with your unit. Very simple.

This gives you a general idea of where the problem is.

From the noise you mentioned on the circuit board it could be the problem but it should be tested before replacing or you might spend some $$ you do not need to spend. We do not have miricle cure's here but we try to work with people as best we can over a long distance. Since we cannot look at your machine and test items to see if they are bad we have to depend upon things you tell us.

Thank you for your help. I will check the circuit board again, but I do not remember seeing any lights at all on the board. The only light like I said was on the ignightor coming from the natural gas line.

As I said most of the boards have a indicator. I cannot find a manual for your furnace so I am no help there also.

It seems as though the noise is coming from what appears to be a relay. Do you know if they are replaceable?